近日，德国柏林洪堡大学的Felix Tebbenjohanns等人合作并取得一项新进展。经过不懈努力，他们成功预测了源于级联量子系统超辐射发射中的相关性。相关研究成果已于2024年10月17日在国际知名学术期刊《物理评论A》上发表。

为解决这一挑战，该研究团队开发了一种基于截断Wigner自旋近似的模拟技术。该研究的随机模拟工具能够预测二阶量子相干函数g⁽²⁾，以及由强激发两级发射体级联系统发射的光场的其他相关函数。因此，该方法为分析包含大量粒子的级联量子系统提供了一种有效且可扩展的方法。

据悉，近期实验中，人们利用纳米光纤耦合的冷原子系综实现了一种新型的级联量子系统。该系统能够研究多达上千个原子高度激发集体自旋态的超辐射衰减，其特点是由波导模式介导的单向耦合。由于大规模多激发系综以及原子间级联相互作用的复杂性，传统模拟方法无法预测超辐射发射的一阶以上相关性。

附：英文原文

Title: Predicting correlations in superradiant emission from a cascaded quantum system

Author: Felix Tebbenjohanns, Christopher D. Mink, Constanze Bach, Arno Rauschenbeutel, Michael Fleischhauer

Issue&Volume: 2024/10/17

Abstract: In recent experiments, a novel type of cascaded quantum system has been realized using nanofiber-coupled cold atomic ensembles. This setup has enabled the study of superradiant decay of highly excited collective spin states of up to a thousand atoms, featuring unidirectional coupling mediated by the waveguide mode. The complexity arising from the large, multi-excited ensemble and the cascaded interactions between atoms makes conventional simulation methods unsuitable for predicting the correlations of superradiant emission beyond the first order. To address this challenge, we developed a simulation technique based on the truncated Wigner approximation for spins. Our stochastic simulation tool can predict the second-order quantum coherence function, g⁽²⁾, along with other correlators of the light field emitted by a strongly excited cascaded system of two-level emitters. This approach thus provides an effective and scalable method for analyzing cascaded quantum systems with large numbers of particles.

DOI: 10.1103/PhysRevA.110.043713

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.043713